1. Field of the Invention
The present invention relates to a spindle positioning means, and in particular to a spindle positioning means of a linear actuator.
2. Description of Prior Art
Linear actuator is used to drive a lead screw to rotate via a motor and a driving assembly including a worm screw and worm wheels. The lead screw drives a connected telescopic pipe to extend or retreat linearly. Thus, the linear actuator is widely applied to many apparatuses such as a hospital bed, electric chair or other fields in which an extending or retreating action is needed. Usually, the worm screw in a common linear actuator extends from the spindle center of the motor directly or is connected to the spindle center of the motor via a coupler. One end of the worm screw (i.e. the spindle center of the motor) away from the motor is formed with a free end naturally. During the transmission between the worm screw and the worm wheels, the worm screw is subjected a relatively large torsion force. Since the worm screw is supported at one side, the worm screw may be broken easily during the transmission between the worm screw and the worm wheels. Therefore, the Inventor aims to improve the conventional linear actuators.
In order to overcome the drawbacks of conventional linear actuators, the manufacturers in this field utilize materials of high strength to make the motor spindle. In addition to high price, such a high-strength spindle cannot be machined easily during the manufacturing process. Thus, such a product is high in price, so that it cannot be widely used in the industry. Most manufacturers utilizes the process shown in FIG. 1 to manufacture the linear actuator, in which a cover b on the worm screw a is provided with a supporting hole c whose diameter is significantly larger than that of the free end of the worm screw a, thereby using the supporting hole c to partially support the free end of the worm screw a. However, such a way of partially supporting the worm screw cannot overcome the problem that the worm screw may be broken due to a lateral action force. Therefore, there is still room for improvement.